fix #3477: NPE in view state management

3 files changed, 13 insertions, 4 deletions

diff --git a/main/src/cgeo/geocaching/activity/AbstractViewPagerActivity.java b/main/src/cgeo/geocaching/activity/AbstractViewPagerActivity.java
index 24c0a1b..049fc7d 100644
--- a/main/src/cgeo/geocaching/activity/AbstractViewPagerActivity.java
+++ b/main/src/cgeo/geocaching/activity/AbstractViewPagerActivity.java
@@ -8,6 +8,7 @@ import com.viewpagerindicator.TitleProvider;
 
 import org.apache.commons.lang3.tuple.Pair;
 import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
 
 import android.app.Activity;
 import android.os.Bundle;
@@ -86,7 +87,8 @@ public abstract class AbstractViewPagerActivity<Page extends Enum<Page>> extends
         /**
          * Gets state of the view
          */
-        public Bundle getViewState();
+        public @Nullable
+        Bundle getViewState();
 
         /**
          * Set the state of the view
@@ -115,8 +117,11 @@ public abstract class AbstractViewPagerActivity<Page extends Enum<Page>> extends
             // Store the state of the view if the page supports it
             PageViewCreator creator = viewCreators.get(page);
             if (creator != null) {
+                @Nullable
                 Bundle state = creator.getViewState();
-                viewStates.put(page, state);
+                if (state != null) {
+                    viewStates.put(page, state);
+                }
             }
 
             container.removeView((View) object);
diff --git a/main/src/cgeo/geocaching/ui/AbstractCachingListViewPageViewCreator.java b/main/src/cgeo/geocaching/ui/AbstractCachingListViewPageViewCreator.java
index 11a37aa..799b695 100644
--- a/main/src/cgeo/geocaching/ui/AbstractCachingListViewPageViewCreator.java
+++ b/main/src/cgeo/geocaching/ui/AbstractCachingListViewPageViewCreator.java
@@ -3,6 +3,7 @@ package cgeo.geocaching.ui;
 import cgeo.geocaching.activity.AbstractViewPagerActivity.PageViewCreator;
 
 import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
 
 import android.os.Bundle;
 import android.support.v4.view.ViewPager;
@@ -24,7 +25,8 @@ public abstract class AbstractCachingListViewPageViewCreator extends AbstractCac
      * @return the state encapsulated in a bundle
      */
     @Override
-    public Bundle getViewState() {
+    public @Nullable
+    Bundle getViewState() {
         if (view == null) {
             return null;
         }
diff --git a/main/src/cgeo/geocaching/ui/AbstractCachingPageViewCreator.java b/main/src/cgeo/geocaching/ui/AbstractCachingPageViewCreator.java
index 9d87f2b..ed5d182 100644
--- a/main/src/cgeo/geocaching/ui/AbstractCachingPageViewCreator.java
+++ b/main/src/cgeo/geocaching/ui/AbstractCachingPageViewCreator.java
@@ -5,6 +5,7 @@ import cgeo.geocaching.activity.AbstractViewPagerActivity.PageViewCreator;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 
 import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
 
 import android.os.Bundle;
 import android.view.View;
@@ -42,7 +43,8 @@ public abstract class AbstractCachingPageViewCreator<ViewClass extends View> imp
      * @return empty bundle
      */
     @Override
-    public Bundle getViewState() {
+    public @Nullable
+    Bundle getViewState() {
         return new Bundle();
     }